Various types of medical devices may be implanted in a person's body to assist normal body functions or to provide therapeutic functions. One example is a nerve stimulator which may be implanted for therapeutic purposes to act on the nerves in a person's body.
Such an implanted device may need to be supplied with power from outside the body for recharging batteries or for operating the device. Similarly, some devices require data transfer by telemetry. High frequency transfer to the implanted device requires an implanted receiving coil receiving high frequency power from a transmitter antenna coil at the outside of the body. Of course, the transmitter coil and receiver coil must be properly positioned relative to each other as to be coupled with each other for maximum transfer of high frequency power Proper position may be difficult when the precise location of the implanted receiver coil is not known.
High frequency power may be transmitted at approximately 2 MHz (VHF) or at 70 MHz (VHF) or more.